The electric potential at the surface of an atomic nucleus $(Z=50)$ of radius $9 \times 10^{-15} \,m$ is

Which physical quantity is measured in barn?

Which of the following is true for a sample of $U^{235}$ and $U^{238}$ isotopes?

If the nuclear radius of ${}_{13}^{27}Al$ is $3.6 \, fm$,the approximate nuclear radius of ${}_{29}^{64}Cu$ in fermi is .......... $fm$.

The maximum potential energy due to electrostatic repulsion between two hydrogen nuclei is nearly (radius of the nucleus $= 1.1 \ Fermi$). $\left[ \frac{1}{4 \pi \epsilon_0} = 9 \times 10^9 \ N \ m^2 \ C^{-2} \right]$ (in $MeV$)

In a periodic table,the average atomic mass of magnesium is given as $24.312 \; u$. This average value is based on their relative natural abundance on Earth. The three isotopes and their masses are $_{12}^{24} Mg \; (23.98504 \; u)$,$_{12}^{25} Mg \; (24.98584 \; u)$,and $_{12}^{26} Mg \; (25.98259 \; u)$. The natural abundance of $_{12}^{24} Mg$ is $78.99 \%$. Calculate the abundances of the other two isotopes.